| − | A group of cells that prepare and release a chemical for use by the body.<ref>Wile, Dr. Jay L. ''Exploring Creation With General Science''. Anderson: Apologia Educational Ministries, Inc. | + | A group of cells that prepare and release a [[chemical]] for use by the [[body]].<ref>Wile, Dr. Jay L. ''Exploring Creation With General Science''. Anderson: Apologia Educational Ministries, Inc. |